Problem: The expression $\dfrac12bh$ gives the area of a triangle where $b$ is the base of the triangle and $h$ is the height of the triangle. What is the area of a triangle with a base of $7 \text{ cm}$ and a height of $4 \text{ cm}$ ?
Answer: A base of $7 \text{ cm}$ and a height of $4 \text{ cm}$ tells us that $b=7$ and $h=4$. Let's substitute $b={7}$ and $h={4}$ into the expression and evaluate: $\begin{aligned} &\phantom{=}\dfrac12bh\\\\ &= \dfrac12({7})({4})\\\\ &= \dfrac12(28)\\\\ &= {14} \end{aligned}$ A triangle with a base of $7 \text{ cm}$ and a height of $4 \text{ cm}$ has an area of ${14} \text{ cm}^2$.